Dopamine D2 Receptor Blockade by Haloperidol 3H-Raclopride Reveals Much Higher Occupancy than EEDQ

摘要: Two techniques are commonly used to measure antipsychotic induced dopamine D2 occupancy in animals: competition with a reversible radioligand (3H-raclopride) or an irreversible receptor inactivator (EEDQ). While both of these have been the past, there is no direct and systematic comparison. In first comparison two methods we find that dose haloperidol required for blocking 50% receptors was 0.02 mg/kg/sc (95% CI 0.018–0.022 mg/kg) as measured using 3H-raclopride method; but significantly higher EEDQ method 0.14 mg/kg/s.c. 0.048–0.224 mg/kg). The showed lesser variance (p = 0.02) despite sensitivity. This seven-fold difference sensitivity antipsychotic-induced explains discrepancies previous studies which also suggest future more sensitive and, likely, valid reflector true occupancy.